1. Field of the Invention
The present invention relates generally to the art of beverage brewing and warming equipment, e.g. of the type used to brew coffee from ground coffee beans. More specifically, the invention relates in its preferred form to an improved drip coffee brewing system in which the fluid, before and/or after brewing takes place, is treated with a magnetic water treatment system and/or by the direct injection into the fluid of electromagnetic radiation, preferably in the radio frequency range. The present invention also relates to the reduction in the amount of coffee required for brewing and to the elimination of the bitterness which arises during brewing and upon standing. Methods of improving the holding or warming of brewed beverages are also described herein.
2. Background in the Art
It has been known for a long time that beverages can be brewed by mixing a ground substance (e.g., coffee or tea) with a heated liquid and extracting therefrom a beverage. The extraction typically is done using some form of filter.
Automatic drip coffee makers are extremely popular because they are quick, inexpensive and convenient. Unlike "perk" coffee makers which recycle the beverage over the grounds, drip coffee makers and similar devices for other beverages rely on a one pass flow of heated water over the powdered coffee, and a typical system includes a number of standard components.
Usually a water reservior is provided which includes an immersion element for generating a stream of hot water, through a conduit, to an outlet located above a chamber. The chamber holds a filter (e.g. a paper filter) into which a powdered material (e.g. ground coffee) is placed. The water flows from the outlet, through the grounds and filter and typically through some sort of discharge outlet into a suitable receiver, such as a pot. The pot, in turn, typically rests on an AC heating plate for being maintained at a desirable drinking temperature (140.degree. F.-180.degree. F.) A similar brewing process occurs in drip makers in which a filter holder is located over a cup or pot and boiling water is deposited into the filter after having been heated on a stove or other device.
One major problem with such devices relates to the amount of coffee required, due in part to the one pass of the brewing fluid into the chamber. Grinding the coffee beans to a smaller average particle size does increase surface area and extraction rate, but this technique, leading to what is commonly referred to as an "auto-drip" grind, is not a complete solution to the problem.
In addition, coffee and tea have a tendency toward bitterness when brewed in drip, perk or other devices, and anyone familiar with the taste of coffee after it has been allowed to stand on an auto-drip burner for more than thirty minutes or so can attest to the increase in bitterness over time. In addition to taste deterioration, the beverage has a tendency to cloud on standing. These attributes may be caused in part by evaporation (i.e. concentration), but we have determined that they are also caused in significant part by the exposure of the beverage to the AC heating plate.
It would be highly desirable to provide a beverage brewing and warming system which could overcome these two principal problems of the prior and existing art.
Treatment of water to improve its properties for a variety of industrial and residential applications has been widely discussed in the scientific literature and in patents issued in the United States and other countries. The variety of devices for such treatment is so great that a comprehensive review thereof will not be undertaken here, it being generally known that such systems have been proposed based on technologies including static and dynamic magnetic treatment, treatment using electrostatic fields, ultrasound, externally generated heating radiation (such as a microwave), directly injected electromagnetic radiation, and, of course, a variety of chemical treatment techniques.
The scientific basis for the effects of various water treatment techniques has been widely debated and discussed, and opinions in the scientific community vary dramatically about the potential for such treatement techniques on an industrial or commercial scale. For example, in the Soviet Union, magnetic treatment of water to assist in removal or prevention of scale has been reported. Favorable analysis of such treatment has been criticized by literature generated in the United States. Some of the theories discussed include one which advocates a belief that magnetic treatment decreases the surface tension of the water molecules, thereby making it "wetter" than untreated water. Another advocates the belief that the magnetic fields generated within the water act only on the impurities contained within the water. Others relate to ionic charge theory, minor changes in the pH, changes in the zeta potential or the like.
Despite such debate over the scientific basis of the treatment effect, a number of individuals and companies are continuing to suggest new types of treatment devices for previously discussed applications and new technologies for unrelated and surprisingly diverse applications.
Examples of magnetic water treatment devices include the following:
Stickler, et al. U.S. Pat. No. 4,746,425 issued May 24, 1988 for "Cooling System For Magnetic Water Treating Device" and Stickler, et al. U.S. Pat. No. 4,659,479 issued Apr. 21, 1987 for "Electromagnetic Water Treating Device". Both Stickler, et al. patents use a pipe core of alternating magnetic and non-magnetic sections with an electromagnet surrounding the pipe through which the fluid to be treated passes.
Another treatment system is disclosed in Larson, et al. U.S. Pat. No. 4,865,747. An electromagnetic field having a voltage which operates in the range of 1 KHz to 1000 MHz is applied to a non-ferromagnetic conduit in which a ferromagnetic core is mounted. The core acts as a sacrificial anode and as a receiving antenna for the radiofrequency electromagnetic radiation.
A permanent magnet system is described in Mitchell U.S. Pat. No. 4,808,306, issued Feb. 28, 1989 for "Apparatus For Magnetically Treating Fluids" The field generator is mounted on one side of the pipe in a non-ferromagnetic housing and the magnet itself has an odd number of sections of alternating polarity. For fuel treatment the uppermost section is desirably a south polar magnetic field, while if water is to be treated, a north polar magnetic field is preferably located upstream. A ferromagnetic plate mounted adjacent to but outwardly from the pipe is used for increasing magnetic field strength. Mitchell indicates that his device can lead to fuel consumption savings, to maintain minerals and other contaminates of water in solution (softening of water), prevention of scale and rust and to improve the taste, cleaning and solvent properties of water.
Additional patents which refer to the use of magnets to treat water include Carpenter's U.S. Pat. No. 4,367,143 issued Jan. 4, 1983 for "Apparatus For Magnetically Treating Liquid Flowing Through A Pipe And Clamping Means Therefor". This patent discusses applying a plurality of strips of ferromagnetic material contained in a shoe member on the outside of a pipe, the number of magnet strips and the power of the magnets being selected for a particular pipe size. The polarity of the magnets in each strip are aligned in the same way, e.g. all south polar ends being oriented upstream with respect to water flow. See also Kulish U.S. Pat. No. 4,605,498 issued Aug. 12, 1986 for "Apparatus For Magnetic Treatment Of Liquids". The magnet arrangement of this patent (surrounding arcuate shape magnets) is such that the south pole magnetic fields are concentrated toward the axis of a pipe, while the north poles are directed radially outwardly.
These patents are representative of the wide diversity of treatment techniques discussed in the art and it is important for a more complete understanding of the prior art to read the "Background" sections of each of the foregoing patents (and the other two patents referred to later herein). Also the tabular listings of art cited against such patents should be reviewed. Each of the background disclosures and listings is incorporated herein and is made available by the copies of the patents supplied herewith.
A unique magnet arrangement for water treatment is disclosed in U.S. Pat. No. 4,888,113 issued to Robert R. Holcomb on Dec. 19, 1989 for "Magnetic Water Treatment Device". In this patent, Dr. Holcomb discusses the use of a plurality of rectangular magnets attached to the exterior of a pipe. The magnets are arranged in pairs adjacent the pipe such that the positive pole of one pair is oriented to one end of a support housing and the negative pole is oriented toward the other end of the housing. Another similarly constructed housing is secured to the opposite side of the pipe, the second housing also including a pair of magnets oriented in a reverse manner from those in the first housing. Thus the positive pole of the first set faces the negative pole of the second set to cause an "attractive" mode of magnetic flux treatment. Applications such as scale prevention, as well as use in washing machines, swimming pools, ice rinks, livestock watering and coffee brewing are suggested. The patent also suggests that the taste of treated water is superior to that of untreated water. The patent further mentions that the magnetic force fields can be generated through wound iron coils coupled to a DC generator. The arrangement of four facing magnetic surfaces described in the Holcomb patent will hereafter be referred to a quadrapolar magnetic treatment system.
Another water treatment technique is that disclosed in U.S. Pat. No. 4,865,748 issued Sep. 12, 1989 to Dwain Morse and entitled "Method And System For Variable Frequency Electromagnetic Water Treatment". In this device, a non-insulated conductor in direct contact with a fluid to be treated is coupled to a generator of electromagnetic radiation, preferably in the radio frequency range. According to the patent, the radiation is injected at a frequency which is related to the electromagnetic radiation absorbtion or emission profile of the particular system being treated. This patent also focuses on the use of that system for the elimination and prevention of scale build-up in boiler systems and the like.
The present invention relates not only to the treatment of water prior to brewing a beverage and the treatment of the brewed beverage to maintain flavor, but it also relates to warming systems for maintaining the brewed beverage in a desirable warm condition without the creation of bitter taste or oil separation. Accordingly, it is desirable at this stage to describe several patents which employ what will be described here as "non-conventional" heating techniques. A "conventional" technique would be any of the well known AC heating devices, such as those commonly available in residential and commercial auto-drip coffee makers. These typically employ an AC resistance type heater which, as discovered by the present inventors, in turn gives off fields which are undesirable for maintaining coffee in its most desirable flavorful mode for extended periods.
Before proceeding to a description of such coffee heating devices, it should be mentioned that another magnetic treatment descaling system is being sold for use with auto-drip coffee installations. It is said by the manufacturer of this device, Aqua-Flo, Inc. of Baltimore, Md., that use of its ceramic ferromagnetic treatement device on the incoming water pipe results in better tasting coffee (as determined by a test panel) having greater solids absorbtion and greater holding time. The heater system in the illustration of the Aqua-Flo device (as illustrated in the sales materials furnished herewith) would be classified in the "conventional" catagory as defined in the preceding paragraph and the suggested advantage of the device is said to result from a projected improvement of the water system based on the descaling characteristics of the magnets.
Non-typical beverage brewing systems are most frequently encountered as 12 or 110 volt conversion brewers for automobiles, recreational vehicles and the like. See, for example, Kimun, U.S. Pat. No. 4,713,522 issued Dec. 15, 1987 and entitled "Electric Heating Appliance Detachably Mounted In A Motor Vehicle" and Walters, et al. U.S. Pat. No. 4,082,939 issued Apr. 4, 1978 for "Vehicular Coffee Heater". Both patents, and the patent documents referred to therein are of this general type. Also known are battery powered heaters for liquids, such as Fisher, et al. U.S. Pat. No. 3,931,494 issued Jan. 6, 1976 for "Recharable Battery Heating Unit". This patent discloses a warming container for a pot or cup which includes a heating element connected to a recharagble battery and switch.
It would be highly desirable to provide a beverage brewing system which leads to improved coffee taste upon brewing, with decreased usage of ground coffee (or other beverage) and which could maintain the desirable taste for an extended period following completion of the brewing cycle.